Dynamics properties of membrane proteins in native cell membranes revealed by solid-state NMR spectroscopy

Cell membranes provide an environment that is essential to the functions of membrane proteins. Cell membranes are mainly composed of proteins and highly diverse phospholipids. The influence of diverse lipid compositions of native cell membranes on the dynamics of the embedded membrane proteins has not been examined. Here we employ solid-state NMR to investigate the dynamics of E. coli Aquaporin Z (AqpZ) in its native inner cell membranes, and reveal the influence of diverse lipid compositions on the dynamics of AqpZ by comparing it in native cell membranes to that in POPC/POPG bilayers. We demonstrate that the dynamic rigidity of AqpZ generally conserves in both native cell membranes and POPC/POPG bilayers, due to its tightly packed tetrameric structure. In the gel and the liquid crystal phases of lipids, our experimental results show that AqpZ is more dynamic in native cell membranes than that in POPC/POPG bilayers. In addition, we observe that phase transitions of lipids in native membranes are less sensitive to temperature variations compared with that in POPC/POPG bilayers, which results in that the dynamics of AqpZ is less affected by the phase transitions of lipids in native cell membranes than that in POPC/POPG bilayers. This study provides new insights into the dynamics of membrane proteins in native cell membranes.

A prototype protein nanocage minimized from carboxysomes with gated oxygen permeability

Protein nanocages (PNCs) in cells and viruses have inspired the development of self-assembling protein nanomaterials for various purposes. Despite the successful creation of artificial PNCs, the de novo design of PNCs with defined permeability remains challenging. Here, we report a prototype oxygen-impermeable PNC (OIPNC) assembled from the vertex protein of the β-carboxysome shell, CcmL, with quantum dots as the template via interfacial engineering. The structure of the cage was solved at the atomic scale by combined solid-state NMR spectroscopy and cryoelectron microscopy, showing icosahedral assembly of CcmL pentamers with highly conserved interpentamer interfaces. Moreover, a gating mechanism was established by reversibly blocking the pores of the cage with molecular patches. Thus, the oxygen permeability, which was probed by an oxygen sensor inside the cage, can be completely controlled. The CcmL OIPNC represents a PNC platform for oxygen-sensitive or oxygen-responsive storage, catalysis, delivery, sensing, etc.

Repurposing Ivermectin to augment chemotherapy's efficacy in osteosarcoma

BACKGROUND

Osteosarcoma is the most frequent malignant bone malignancy and the current treatments are ineffective. Ivermectin, an anti-protozoal drug, has been shown to have anti-cancer activity. This work investigated the potential of repurposing ivermectin to augment chemotherapy's efficacy in osteosarcoma.

METHODS

Proliferation, migration and apoptosis assays were performed in ivermectin-treated osteosarcoma cells. Combination studies were performed. Osteosarcoma xenograft mouse model was established to investigate the in vivo efficacy of ivermectin. Intracellular reactive oxygen species (ROS) and mitochondrial superoxide, membrane potential, ATP, 8-OHdG level, protein carbonylation and lipid peroxidation were determined after ivermectin treatment.

RESULTS

Ivermectin was effective and acted synergistically with doxorubicin in osteosarcoma cells regardless of cellular origin and genetic profiling. This was achieved through suppressing inhibiting growth and migration, and inducing caspase-dependent apoptosis. Ivermectin also significantly inhibited osteosarcoma growth in vivo and its combination with doxorubicin resulted in much greater efficacy than doxorubicin alone. Importantly, the effective dose of ivermectin was clinically feasible and did not cause significant toxicity in mice. Mechanistical analysis showed that ivermectin induced oxidative stress and damage, and mitochondrial dysfunction.

CONCLUSIONS

Our findings indicate that ivermectin has utility in treating patients with osteosarcoma, especially those resistant to chemotherapy.

Resting-state functional magnetic resonance imaging-based identification of altered brain the fractional amplitude of low frequency fluctuation in adolescent major depressive disorder patients undergoing electroconvulsive therapy

PURPOSE

While electroconvulsive therapy (ECT) has been repeatedly been shown to effectively and efficiently treat the major depressive disorder (MDD), the mechanistic basis for such therapeutic efficacy remains to be firmly established. As such, further research exploring the ECT-based treatment of MDD in an adolescent population is warranted.

METHODS

This study included 30 treatment-naïve first-episode MDD patients and 30 healthy control (HC) individuals (aged 12-17 years). All participants were scanned using rs-fMRI, and the 30 MDD patients were scanned again after 2 weeks of the ECT treatment period. Intrinsic local activity in each voxel was assessed based on the fractional amplitude of low frequency fluctuation (fALFF) parameter, with all fALFF analyses being completed using the REST application. Correlations between ECT-related changes in fALFF and clinical parameters were additionally examined.

RESULTS

Relative to HCs, MDD patients exhibited increased fALFF values in the right inferior frontal gyrus (ORBinf), inferior occipital gyrus (IOG), and the left middle frontal gyrus (MFG) at baseline. Following ECT, these patients exhibited significant increases in fALFF values in the right medial superior frontal gyrus (SFGmed), dorsolateral superior frontal gyrus (SFGdor), anterior cingulate, and paracingulate gyrus (ACG), median cingulate and paracingulate gyrus (DCG), and left MFG. MDD patient HAMD scores were negatively correlated with fALFF values when analyzing pre-ECT vs. post-HCT ΔHAMD and fALFF values in the right SFGmed, SFGdor, and the left MFG.

CONCLUSION

These data suggest that ECT induced altered fALFF in some regions of the brain, suggesting that these alterations may serve as a neurobiological indicator of ECT effectiveness in MDD adolescents.

Assessment of automated craving across substances and across cultures: stability-analysis of the Craving Automated Scale (CAS)

BACKGROUND

The transition from hedonic to compulsive use in Substance Use Disorders (SUD) is a critical point in SUD progression and hence relevant for assessment and treatment. To measure the habitual patterns of substance consumption, the Craving Automated Scales (CAS) for alcohol (CAS-A), substances (CAS-S) and cigarette smoking (CAS-CS) were developed and introduced to different countries. In this study, we aimed to investigate the structural stability of CAS across substances and cultures.

METHODS

This study analyzed the CAS-scores of a sample of 370 participants in Germany, China and the UK, including 262 opioid-users, 65 smokers and 43 alcohol-users. We performed stability analyses to check the stability (i. e. factorial invariance) of factor solutions. Based on confirmed stability of the general factor (gfactor) solution and the calculations rule obtained in the previous validation of CAS-alcohol (CAS-A), the factor structures of CAS-A, CAS-S and CAS-CS were compared.

RESULTS

The gfactor solutions based on calculations rule shows good stability, with the mean stability coefficients of 0.990 and 0.977 for CAS-S and CAS-CS respectively. The gfactor patterns were similar for CAS-A, CAS-S and CAS-CS, as well as across samples (Germany, China and the UK), with most factor-loadings larger than 0.7. Based on these findings, CAS-S and CAS-CS were also associated with established clinical measures of SUD.

CONCLUSIONS

Our findings suggest the two-gfactor solution based on a proposed calculation rule has a high stability across substances and cultures. This could be in line with common neurobiological mechanisms underlying habitual substance use. Moreover, comparing CAS with established clinical tools suggests that CAS might assess the automated behavior in substance consumption in a more sophisticated way.

Impact of La Concentration on Ferroelectricity of La-Doped HfO2 Epitaxial Thin Films

Epitaxial thin films of HfO₂ doped with La have been grown on SrTiO₃(001) and Si(001), and the impact of the La concentration on the stabilization of the ferroelectric phase has been determined. Films with 2-5 at. % La doping present the least amount of paraelectric monoclinic and cubic phases and exhibit the highest polarization, having a remanent polarization above 20 μC/cm². The dopant concentration results in an important effect on the coercive field, which is reduced with increasing La content. Combined high polarization, high retention, and high endurance of at least 10¹⁰ cycles is obtained in 5 at. % La-doped films.

Extensively sparse 13C labeling to simplify solid-state NMR 13C spectra of membrane proteins

Solid-state Nuclear Magnetic Resonance (ssNMR) is an emerging technique to investigate the structures and dynamics of membrane proteins in an artificial or native membrane environment. However, the structural studies of proteins by ssNMR are usually prolonged or impeded by signal assignments, especially the assignments of signals for collection of distance restraints, because of serious overlapping of signals in 2D ¹³C-¹³C spectra. Sparse labeling of ¹³C spins is an effective approach to simplify the ¹³C spectra and facilitate the extractions of distance restraints. Here, we propose a new reverse labeling combination of six types of amino acid residues (Ile, Leu, Phe, Trp, Tyr and Lys), and show a clean reverse labeling effect on a model membrane protein E. coli aquaporin Z (AqpZ). We further combine this reverse labeling combination and alternate ¹³C-¹²C labeling, and demonstrate an enhanced dilution effect in ¹³C-¹³C spectra. In addition, the influences of reverse labeling on the labeling of the other types of residues are quantitatively analyzed in the two strategies (1, reverse labeling and 2, reverse labeling combining alternate ¹³C-¹²C labeling). The signal intensities of some other types of residues in 2D ¹³C-¹³C spectra are observed to be 20-50% weaker because of the unwanted reverse labeling. The extensively sparse ¹³C labeling proposed in this study is expected to be useful in the collection of distance restraints using 2D ¹³C-¹³C spectra of membrane proteins.

Cannabis and orofacial pain: a systematic review

The naturally occurring cannabis plant has played an established role in pain management throughout recorded history. However, in recent years, both natural and synthetic cannabis-based products for medicinal use (CBPM) have gained increasing worldwide attention due to growing evidence supporting their use in alleviating chronic inflammatory and neuropathic pain associated with an array of conditions. In view of these products' growing popularity in both the medical and commercial fields, we carried out a systematic review to ascertain the effects of cannabis and its synthetically derived products on orofacial pain and inflammation. The application of topical dermal cannabidiol formulation has shown positive findings such as reducing pain and improving muscle function in patients suffering from myofascial pain. Conversely, two orally-administered synthetic cannabinoid receptor agonists (AZD1940 and GW842166) failed to demonstrate significant analgesic effects following surgical third molar removal. There is a paucity of literature pertaining to the effects of cannabis-based products in the orofacial region; however, there is a wealth of high-quality evidence supporting their use for treating chronic nociceptive and neuropathic pain conditions in other areas. Further research is warranted to explore and substantiate the therapeutic role of CBPMs in the context of orofacial pain and inflammation. As evidence supporting their use expands, healthcare professionals should pay close attention to outcomes and changes to legislation that may impact and potentially benefit their patients.

Anomalous functional connectivity within the default-mode network in treatment-naive patients possessing first-episode major depressive disorder

BACKGROUND AND OBJECTIVE

Previous studies have shown that the default-mode network (DMN) has a substantial role in patients with major depressive disorder (MDD). However, there is a shortage of information regarding variations in the functional connectivity (FC) of the DMN of treatment-naive patients with first-episode MDD. The present study aims to explore the FC of the DMN in such patients.

METHODS

The study population consisted of 33 patients and 35 controls, paired regarding age, gender, education level, and health condition. Depression severity was assessed through the Hamilton Depression Scale (HAM-D), and subjects underwent evaluation during the resting-state through functional magnetic resonance imaging (rs-fMRI). To assess the result, we used FC and ICA. We used Spearman's correlation test to detect potential correlations between anomalous FC and severity of HAM-D scores.

RESULTS

We have found a decreased FC in the left medial orbitofrontal gyrus (MOFG) and right marginal gyrus (SMG) in depressive patients compared to controls. There was a negative correlation between abnormal FC in the right SMG and HAM-D scores. We have not found any increase in FC of the DMN in treatment-naive, first-episode of MDD patients.

CONCLUSIONS

Our study provided evidence of a negative correlation between abnormal FC in the DMN and severity of depression symptoms measured by HAM-D in treatment-naive MDD patients. This finding could shed some light on the relevance of DMN for understanding the pathophysiology of cognitive impairment in MDD.

Non-volatile optical switch of resistance in photoferroelectric tunnel junctions

In the quest for energy efficient and fast memory elements, optically controlled ferroelectric memories are promising candidates. Here, we show that, by taking advantage of the imprint electric field existing in the nanometric BaTiO3 films and their photovoltaic response at visible light, the polarization of suitably written domains can be reversed under illumination. We exploit this effect to trigger and measure the associate change of resistance in tunnel devices. We show that engineering the device structure by inserting an auxiliary dielectric layer, the electroresistance increases by a factor near 2 × 103%, and a robust electric and optic cycling of the device can be obtained mimicking the operation of a memory device under dual control of light and electric fields.

A dual enhanced anti-bacterial strategy based on high chlorin e6-loaded polyethyleneimine functionalized graphene

Bacterial infection has always been a long-term problem of human history and has nowadays became a severe threat to human health with the appearance of drug-resistant bacteria due to the abuse of antibiotics. In this study, a high chlorin e6 (Ce6) photosensitizer-loaded polyethyleneimine-functionalized graphene (PEI-G) nanocomposite (PEI-G@Ce6) was prepared. The loading capacity of Ce6 on PEI-G@Ce6 was approximately up to 32.91 wt%, which was higher than that of other nanomaterials. The as-prepared PEI-G@Ce6 not only improves the photostability of free photosensitizer Ce6 molecules but also maintains the ability of singlet oxygen generation. Based on the dual enhancement of the physical antibacterial effects of PEI-G and the photodynamic therapy (PDT) antibacterial effects of loaded photosensitizer Ce6, PEI-G@Ce6 exhibited enhanced antibacterial efficiency towards Staphylococcus aureus. Therefore, the present strategy provided an effective platform to improve antibacterial efficiency for the better treatment of wound infections.

Dual enhanced anti-bacterial strategy based on a high chlorin e6-loaded polyethyleneimine functionalized graphene nanomaterial.

Robots Under COVID-19 Pandemic: A Comprehensive Survey

As a result of the difficulties brought by COVID-19 and its associated lockdowns, many individuals and companies have turned to robots in order to overcome the challenges of the pandemic. Compared with traditional human labor, robotic and autonomous systems have advantages such as an intrinsic immunity to the virus and an inability for human-robot-human spread of any disease-causing pathogens, though there are still many technical hurdles for the robotics industry to overcome. This survey comprehensively reviews over 200 reports covering robotic systems which have emerged or have been repurposed during the past several months, to provide insights to both academia and industry. In each chapter, we cover both the advantages and the challenges for each robot, finding that robotics systems are overall apt solutions for dealing with many of the problems brought on by COVID-19, including: diagnosis, screening, disinfection, surgery, telehealth, care, logistics, manufacturing and broader interpersonal problems unique to the lockdowns of the pandemic. By discussing the potential new robot capabilities and fields they applied to, we expect the robotics industry to take a leap forward due to this unexpected pandemic.

Letter to the Editor: COVID-19 and Persons with Dementia in Acute Care Settings: How to "EVADE" Challenging Behaviors

The double whammy of dementia and coronavirus disease 2019 (COVID-19) has raised huge concerns for healthcare systems which are already struggling to cope with care demands of persons with dementia (PWD) in non-pandemic times (1). PWD who are admitted to acute care services are particularly vulnerable to behavioural changes and adverse outcomes from delirium (2, 3). During the COVID-19 period, ward relocation is frequently encountered due to COVID-19 screening and segregation; this constant changing of environment and care teams puts PWD at risk of behavioural exacerbations. This is aggravated by restrictive visitor policies in hospitals, depriving PWD of the reassuring presence of family members. Not surprisingly, caring for persons with dementia (PWD) with behavioral issues in acute care settings has become extremely challenging.

MiRNA-300 suppresses proliferation, migration and invasion of non-small cell lung cancer via targeting ETS1

OBJECTIVE

To elucidate the biological function of microRNA-300 (miRNA-300) in influencing the progression of non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

The relative level of miRNA-300 in NSCLC tissues and cells was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The influences of miRNA-300 on the proliferative, migratory, and invasive potentials of A549 cells were assessed. The binding relationship between miRNA-300 and ETS1 was verified by the Dual-Luciferase Reporter Gene Assay. Finally, the regulatory effect of the interactive miRNA-300 and ETS1 on the progression of NSCLC was identified.

RESULTS

MiRNA-300 was downregulated in NSCLC tissues and cells. The overexpression of miRNA-300 suppressed A549 cells to proliferate, migrate, and invade. MiRNA-300 could bind to ETS1 3'UTR and suppress its level in A549 cells. Notably, the knockdown of miRNA-300 could reverse the regulatory role of ETS1 in the cellular behaviors of NSCLC.

CONCLUSIONS

MiRNA-300 suppresses NSCLC to proliferate, migrate, and invade by targeting ETS1.

Selectively Enhanced 1H-1H Correlations in Proton-Detected Solid-State NMR under Ultrafast MAS Conditions

Proton-detected solid-state NMR has emerged as a powerful analytical technique in structural elucidation via ¹H-¹H correlations, which are mostly established by broadband methods. We propose a new class of frequency-selective homonuclear recoupling methods to selectively enhance ¹H-¹H correlations of interest under ultrafast magic-angle spinning (MAS). These methods, dubbed as selective phase-optimized recoupling (SPR), can provide a sensitivity enhancement by a factor of ∼3 over the widely used radio-frequency-driven recoupling (RFDR) to observe ¹H_N-¹H_N contacts in a protonated tripeptide N-formyl-Met-Leu-Phe (fMLF) under 150 kHz MAS and are successfully utilized to probe a long-range ¹H-¹H contact in a pharmaceutical molecule, the hydrochloride form of pioglitazone (PIO-HCl). SPR is not only highly efficient in frequency-selective recoupling but also easy to implement, imparting to it great potential to probe ¹H-¹H contacts for the structural elucidation of organic solids such as proteins and pharmaceuticals under ultrafast MAS conditions.

Local field potential activity dynamics in response to deep brain stimulation of the subthalamic nucleus in Parkinson's disease

Local field potentials (LFPs) may afford insight into the mechanisms of action of deep brain stimulation (DBS) and potential feedback signals for adaptive DBS. In Parkinson's disease (PD) DBS of the subthalamic nucleus (STN) suppresses spontaneous activity in the beta band and drives evoked resonant neural activity (ERNA). Here, we investigate how STN LFP activities change over time following the onset and offset of DBS. To this end we recorded LFPs from the STN in 14 PD patients during long (mean: 181.2 s) and short (14.2 s) blocks of continuous stimulation at 130 Hz. LFP activities were evaluated in the temporal and spectral domains. During long stimulation blocks, the frequency and amplitude of the ERNA decreased before reaching a steady state after ~70 s. Maximal ERNA amplitudes diminished over repeated stimulation blocks. Upon DBS cessation, the ERNA was revealed as an under-damped oscillation, and was more marked and lasted longer after short duration stimulation blocks. In contrast, activity in the beta band suppressed within 0.5 s of continuous DBS onset and drifted less over time. Spontaneous activity was also suppressed in the low gamma band, suggesting that the effects of high frequency stimulation on spontaneous oscillations may not be selective for pathological beta activity. High frequency oscillations were present in only six STN recordings before stimulation onset and their frequency was depressed by stimulation. The different dynamics of the ERNA and beta activity with stimulation imply different DBS mechanisms and may impact how these activities may be used in adaptive feedback.